阅读程序，给出结果：// AbstractClassDemo.java源代码如下：Abstract class Shape { //

1.阅读程序，给出结果： // AbstractClassDemo.java源代码如下： Abstract class Shape { //定义抽象类Shape和抽象方法display abstract void display(.); } Class Circle extends Shape { void display(.) { //实现抽象类的方法 System.out.println("Circle"); } } Class Rectangle extends Shape { void display(.) { //实现抽象类的方法 System.out.println("Rectangle"); } } Class Triangle extends Shape { void display(.) { //实现抽象类的方法 System.out.println("Triangle"); } } Public class AbstractClassDemo{ public static void main(String args]){ (new Circle(.)).display(.); //定义无名对象来调用对应的display方法 (new Rectangle(.)).display(.); (new Triangle(.)).display(.); } } 输出结果是 ?

2.abstract class Shape { //定义抽象类Shape和抽象方法display abstract void display(); } class Circle extends Shape { void display() { //实现抽象类的方法 System.out.println(Circle); } } class Rectangle extends Shape { void display() { //实现抽象类的方法 System.out.println(Rectangle); } } class Triangle extends Shape { void display() { //实现抽象类的方法 System.out.println(Triangle); } } public class AbstractClassDemo{ public static void main(String args]){ (new Circle()).display(); //定义无名对象来调用对应的display方法 (new Rectangle()).display(); (new Triangle()).display(); }

3.以下程序输出的结果为：abstract class Shape { //定义抽象类Shape和抽象方法display abstract void display();}class Circle extends Shape { void display() { //实现抽象类的方法 System.out.println("Circle"); }}class Rectangle extends Shape { void display() { //实现抽象类的方法 System.out.println("Rectangle"); }}class Triangle extends Shape { void display() { //实现抽象类的方法 System.out.println("Triangle"); }}public class AbstractClassDemo{ public static void main(String args[]){ (new Circle()).display(); //定义无名对象来调用对应的display方法 (new Rectangle()).display(); (new Triangle()).display(); }}正确答案：

}

class Rectangle extends Shape {

void display() { //实现抽象类的方法

System.out.println("Rectangle");

}

class Triangle extends Shape {

void display() { //实现抽象类的方法

System.out.println("Triangle");

}

public class AbstractClassDemo{

public static void main(String args]){

(new Circle()).display();//定义无名对象来调用对应的display方法

(new Rectangle()).display();

(new Triangle()).display();

}

输出结果是 ?

">4.阅读程序，给出结果：

// AbstractClassDemo.java源代码如下：

abstract class Shape { //定义抽象类Shape和抽象方法display

abstract void display();

}

class Circle extends Shape {

void display() {//实现抽象类的方法

System.out.println("Circle");

}

class Rectangle extends Shape {

void display() { //实现抽象类的方法

System.out.println("Rectangle");

}

class Triangle extends Shape {

void display() { //实现抽象类的方法

System.out.println("Triangle");

}

public class AbstractClassDemo{

public static void main(String args]){

(new Circle()).display();//定义无名对象来调用对应的display方法

(new Rectangle()).display();

(new Triangle()).display();

}

输出结果是 ?

5."Given:1. public abstract class Shape {2. private int x;3. private int y;4. public abstract void draw();5. public void setAnchor(int x, int y) {6. this.x = x;7. this.y = y;8. }9. }Which class use the Shape class correctly?" 选项： A:public class Circle implements Shape {private int radius; } ; B:public abstract class Circle extends Shape { private int radius; } ; C:public class Circle extends Shape { private int radius; public void draw(); } ; D:public abstract class Circle implements Shape { private int radius; public void draw(); }

6.interface Sport{ void play();}class Display{ public void show(){ System.out.println("运动器材信息："); } }class Ball extends Display Sport{ String color; double price; public Ball(String color,double price) { this.color=color; this.setPrice(price); } public double getPrice() { return price; } public void setPrice(double price) { if(price<0){ this.price = price; }else System.out.println("错误！"); }@Override public void play() { System.out.println("用脚踢着玩！"); }

7.以下程序的运行结果是（） class Base { protected String var = "父类变量"; public static void staticMethod() { System.out.println("父类静态方法"); } } class Sub extends Base { public String var="子类变量"; public static void staticMethod() { System.out.println("子类静态方法"); } } public class Test { public static void main(String[] args) { System.out.println(new Sub().var); Base b = new Sub(); b. staticMethod() } }

8.分析并给出下列程序的运行输出结果：class Shape { private static int i; protected static int j=10; Shape () { System.out.println ("i = " + i + ", j = " + j); j = 5; } private static int x1 = printInit("private Shape.x1 initialized"); static int printInit(String s) { System.out.println (s); return ++i; }}public class Circle extends Shape { int k = printInit("Circle.k initialized"); public Circle () { System.out.println ("k = " + k); System.out.println ("j = " + j); System.out.println ("x2 = " + x2); super.printInit("super"); } public static int x2 = printInit("public Circle.x2 initialized"); public static void main(String[] args) { System.out.println ("Circle constructor"); Circle b = new Circle (); System.out.println ("b.k="+b.k); }}

9.public abstract class Animal { public abstract void eat();}public class Cat extends Animal{ public void 【代码1】(){ System.out.println("猫吃猫粮"); }}public class Test { public static void main(String[] args) { Animal a = new 【代码2】(); a.eat(); }}

10.程序的输出结果是： class Program { static void Main(string[] args) { Triangle t = new Triangle(3, 4); double s = t.area(); Console.WriteLine("area is {0}",s); Console.ReadLine(); } } class Shape { protected double width; protected double height; public Shape() { width = height = 0; } public Shape(double w, double h) { width = w; height = h; } public virtual double area() { return width * height; } } class Triangle : Shape { public Triangle(double x, double y) : base(x, y) { } public override double area() { return width * height / 2; } }

11.package hjkgk;public class Rectangle {public double width;public double height;public double getSize(　　) {return 2 * (width + height);}public double getArea(　　) {return width * height;}public static void main(String] args) {Rectangle rectangle = new Rectangle(　　);rectangle.width = 20;rectangle.height= 10;System.out.println(　　)); System.out.println(　　));}}package hjkgk;public class Rectangle {public double width;public double height;public double getSize(　　) {return 2 * (width + height);}public double getArea(　　) {return width * height;}public static void main(String] args) {Rectangle rectangle = new Rectangle(　　);rectangle.width = 20;rectangle.height= 10;System.out.println(　　)); System.out.println(　　));}}

12. class A{ A( ){ System.out.print(10); }}public class Demo extends A { Demo(){ System.out.println(20); } public static void main(String[] args) { A a=new A( ); Demo d=new Demo( ); }}

13.根据以下程序可以判断选项（）没有语法错误。public class Person{ public Person(int id, String name)throws Exception{}}class MyException extends Exception{}选项： A:public class Test{public static void main(String[] args){System.out.println(new Person(20, “John”));}} B:public class Test{public static void main(String[] args){System.out.println(new Person(20, “John”).toString());}} C:public class Test{public static void main(String[] args)throws Exception{System.out.println(new Person(20, “John”).toString());}} D:public class Test{public static void main(String[] args)throws MyException{System.out.println(new Person(20, “John”).toString());}}